Application specific integrated circuits (ASICs) offer the electronics designer the ability to customize standard integrated circuits (ICs) to provide a unique set of performance characteristics by integrating complex functionality and input/output (I/O) on a single integrated circuit (IC). The significant benefits regarding the use of ASICs are customization, the ability to create unique functionality, and economies of scale for devices destined to be mass-produced. Alternative devices, such as, for example, field programmable gate arrays (FPGAs) permit the digital logic designer access to standard digital logic functions and capabilities, and additionally allow certain functions and I/O to be programmed rather than fixed during production. Programmability offers the advantages of greater design flexibility and faster product implementation during subsequent system development efforts. Furthermore, for purposes of low volume applications and the creation of prototype units, FPGAs typically exhibit lower unit costs than do ASICs. Even though FPGAs are highly flexible (e.g., programmable I/O) and under certain circumstances exhibit lower unit costs, they nevertheless fall short of the primary benefits offered by ASIC's, namely, customization, diverse function complexity and high speed. Also, a circuit technology used for an FPGA may not be suitable to implement a certain feature, for example, a feature requiring a semiconductor technology that is different from the technology used to implement the FPGA. Such specialized features are typically implemented as a standard or special purpose integrated circuit.
Accordingly, there exists a need for an integrated circuit (IC) or a class of ICs that offers the customization and functional diversity of an FPGA combined with another IC that has special characteristics that are not readily implemented on the FPGA.